Door thresholds are used in residential and commercial construction projects to provide a floor covering and support underneath a door. Door thresholds may be referred to as doorsills in some applications. When a door is closed, it is generally desirable for the lower horizontal edge of the door to approach the structure underneath the door in a close gap fit or seal to prevent air drafts, heating, cooling, and/or foreign objects such as insects, weather, or debris from easily passing underneath the door.
Many conventional door thresholds include a wood, metal or composite threshold base that is fixed to a floor or subfloor. The threshold base provides a raised portion in some embodiments that may be locally taller than the surrounding floor. This allows a better seal against the lower edge of the door. Conventional threshold bases may include a threshold base having a base support as well as a tread plate positioned over the base support. Tread plates typically include aluminum or other types of metal, wood, plastic, composite, or other suitable materials and may include a grooved or treaded surface to provide traction when a user steps on the tread plate. Tread plates and/or threshold bases of conventional thresholds generally include a finished surface to be visible when the construction of the door and flooring is complete.
Conventional thresholds also typically include a longitudinal strip of material known as a threshold cap that sits atop the threshold base. The threshold cap may be located directly under the door when the door is closed to provide an optimal gap fit or seal between the threshold cap and the lower edge of the door. The cap may be vertically adjustable in some embodiments to optimize the spacing between the cap and the lower door edge.
Conventional thresholds may be provided as a kit or assembly, including both the threshold cap and the threshold base, wherein the threshold base has base support and tread plate pre-installed thereon. The assembly may be installed in a building during a construction process before or during installation of the door jamb or adjacent framing. It is often necessary to install the threshold assembly before a construction project is complete to allow the door frame carpentry to properly surround the threshold and to allow the flooring to be installed. This means the threshold is fixed in place and is typically not easily removable from a finished door jamb once the surrounding hardware and floor is installed. As such, removal of a door threshold after it has been installed, and after surrounding construction is complete, often requires removal of significant portions of the local door jamb structure and/or flooring.
One problem associated with conventional door thresholds and door threshold assemblies includes physical or cosmetic damage and wear to the threshold base and/or tread plate after the threshold has been installed but before construction is complete. For example, after a threshold has been installed, workers typically continue to work on the surrounding construction. This causes workers to repeatedly walk across and move equipment across the threshold base and/or tread plate, causing inadvertent damage. This damage is often noticeable after the construction job is complete when the surrounding door, door jamb, flooring, and trip carpentry is finished. A damaged threshold base or tread plate from post-installation wear is unsightly and is generally unacceptable to new construction customers. In many applications, customers may demand workers to replace damaged thresholds and/or tread plates after the surrounding construction is complete. In a large building project, this could include replacement of several thresholds. Such replacement requires expensive and timely deconstruction of adjacent door jamb members and/or flooring, resulting in additional cost and time for a construction project.
Others have attempted to overcome the problems of post-installation threshold base and tread plate damage and wear by providing protective film covers on threshold assemblies to prevent damage. For example, some conventional thresholds include a film or removable plastic layer stuck on the threshold base or tread plate. This type of removable layer typically allows a user to peel back the protective film after the surrounding construction is complete. However, such films are often too thin and are inadequate to prevent scratching or denting of threshold bases and tread plates during post-installation use by construction workers. Additionally, such films may begin to peel back prematurely due to wear across the threshold.
Others have attempted to overcome these problems by providing removable plastic shields or covers that may be used to cover a threshold base and cap after installation. Such covers may clip into place on the exterior perimeter of the threshold assembly or tread plate, fitting over both the threshold cap and the threshold base. However, such conventional plastic covers are difficult to keep on the threshold as workers repeatedly walk over the threshold, and these types of covers often become dislodged after installation. When the cover is dislodged, it provides no protection to the threshold base and/or tread plate. Thus, these types of conventional covers are generally inadequate for providing protection to threshold bases and tread plates.
What is needed then are improvements in protective devices for covering thresholds on a construction site.